The present invention relates in general to pre-press proofing and in particular, to an improved lamination apparatus and lamination roller that utilize pressure and heat to laminate media together.
Pre-press proofing is a procedure that is used primarily by the printing industry for creating representative images of printed material. In the printing industry pre-press color proofs are used to check for color balance, control parameters and other important image quality requirements, without the cost and time that is required to actually produce printing plates, set up a printing press and produce an example of a representative image. Pre-press proofing avoids the higher costs and a loss of profits that would ultimately be passed on to the customer.
To create a pre-press proof, an original image is separated into individual color separations or digital files. The original image is scanned and separated into the three subtractive primary colors and black. Typically a color scanner is used to create the color separations or digital files and in some instances, more than four color separations or digital files are used. Although there are several ways used in the printing industry to create a pre-press proof from the color separations or digital files they are generally one of three types. The first method being a color overlay system that employs the representative image on a separate base for each color, which are then overlaid to create a pre-press proof. The second, a single integral sheet process in which the separate colors for the representative image is transferred one at a time by lamination onto a single base. The third, a digital method in which the representative image is produced directly onto a receiver stock, or onto an intermediate sheet then transferred by lamination onto a receiver stock from digital files.
The representative image to be laminated can be created on, but is not limited to, a commercially available Kodak image processing apparatus, depicted in commonly assigned U.S. Pat. No. 5,268,708, which describes an image processing apparatus having half-tone color imaging capabilities. The image processing apparatus is arranged to form a representative image onto a sheet of thermal print media in which colorant from a sheet of colorant donor material is transferred to the thermal print media, by applying thermal energy to the colorant donor sheet material to form the representative image. The image processing apparatus is comprised generally of a material supply assembly and a lathe bed scanning subsystem. The scanning subsystem includes: a lathe bed scanning frame, translation drive, translation stage member, printhead, imaging drum, and media exit transports.
The operation of the image processing apparatus comprises of metering a length of the thermal print media from the material supply assembly. The thermal print media is then measured and cut into sheet form of the required length and transported to the imaging drum, registered, wrapped around, and secured onto the imaging drum. Next, a length of colorant donor material is metered out of the material supply assembly, measured, and cut into sheet form of the required length. It is then transported to the imaging drum and wrapped around the imaging drum utilizing a load roller which is described in detail, in commonly assigned U.S. Pat. No. 5,268,708, such that it is superposed in the desired registration with respect to the thermal print media, which has already been secured to the imaging drum.
After the colorant donor sheet material is secured to the periphery of the imaging drum the scanning subsystem or write engine provides the imaging function. This image function is accomplished by retaining the thermal print media and the colorant donor sheet material on the imaging drum while it is rotated past the printhead. The translation drive traverses the printhead and translation stage member axially along the axis of the imaging drum, in coordinated motion with the rotating imaging drum. These movements combine to produce the representative image on the thermal print media.
Once the representative image has been formed on the thermal print media, the colorant donor sheet material is then removed from the imaging drum. This is accomplished without disturbing the thermal print media that is beneath it. The colorant donor sheet material is then transported out of the image processing apparatus by means of the material exit transport. Additional colorant donor sheet materials featuring other desired colorants are sequentially superimposed with the thermal print media on the imaging drum and then imaged onto the thermal print media as previously mentioned, until the representative image is completed on the thermal print media. The representative image formed thereon is then unloaded from the imaging drum and transported by the receiver sheet material exit transport to an exit tray in the exterior of the image processing apparatus.
After a representative image has been formed on the thermal print media, it is transferred to a receiver stock such that the pre-press proof is representative of the image that will be printed by the printing press. A laminator as described in U.S. Pat. No. 5,478,434 can be used to bond or laminate the representative image as a part of a pre-press proofing system. As additional references, U.S. Pat. No. 5,203,942 describes a laminator that employs a lamination/de-lamination system as applied to a drum laminator and pending U.S. patent application Ser. No. 09/676,877, filed Sep. 29, 2000, U.S. Pat. No. 6,463,981 describes a laminator that employs a first lamination roller and a second lamination roller along with endless belts incorporated into a lamination apparatus. For the purpose of this patent application the laminator described in U.S. patent application Ser. No. 09/676,877 U.S. Pat. No. 6,463,981 will be used. It should be noted that the present invention described in this disclosure is not limited to the laminator referenced above.
The receiver stock can be sheet-fed press printing stock, specially coated paper stock, or previously laminated stock. In this latter case a sheet of pre-laminate, which has a pre-laminate support layer consisting of a suitable base material, optionally coated with a releasing material, and a thermal print layer, is placed on top of a receiver sheet, which is also called receiver stock in the industry. The multiple layers form a lamination sandwich, which is fed into the laminator. Once the lamination sandwich exits the laminator the pre-laminate support layer is peeled away from the now pre-laminated receiver stock. Any of the laminators referred to above can be used to affect the transfer of the pre-laminate receiving layer to the receiver stock.
The above described lamination method works well for most materials and both laser thermal and inkjet pre-press proofs. The upper and lower lamination rollers used in the apparatus described above, however, have a less than desirable failure rate in the form of de-lamination of a deformable layer surrounding a substantially solid core due to the high pressure and temperature requirements during the lamination process. Thus, there exists a need to improve lamination roller life.
The present invention provides, but is not limited to, an improved lamination roller for use in a lamination apparatus used to laminate material to form a pre-press proof used in the graphics industry.
According to one aspect of the present invention a laminator assembly comprises a first lamination roller located on a first side of a media passage; a second lamination roller located on a second side of said media passage so as to oppose said first lamination roller, wherein a nip portion is defined between the first lamination roller and the second lamination roller so as to apply pressure and heat to the media in the media passage which passes through the nip portion. At least one of the first lamination roller and second lamination roller is a lamination roller comprising a substantially solid core which may be solid preferably made of metal. Surrounding the substantially solid core is a first deformable layer having a 60-80 durometer preferably made of a silicone. Surrounding the first deformable layer is a second deformable layer having a 20-60 durometer preferably a silicone-based material.
According to one embodiment, one or more of the rollers can be heated or adapted to accept a heating element while a cross head extrusion method is preferred to form the first and second layers. Other methods well known in the art such casting, molding, shave wrap, or combinations thereof can be used. Typically a bond layer or adhesive layer exists between the substantially solid core and the first deformable layer also between the first and second deformable layer. In the preferred method there would be no bond layer or adhesive layer between the deformable layers. It should be noted that more than two deformable layers could be used depending on the application.
The present invention provides for a lamination roller that increase the life of the lamination roller or rollers due to the heat and stresses of the application, and can be used in laminators or any number of devices, including copiers and fax machines.
According to a feature of the present invention, a laminating system for bonding an image, to a receiver stock, a thermal print media of the type including a carrier and a material to be applied to the receiver stock, having a pair of lamination rollers with at least one of the lamination roller having been improved by having at least two deformable layers. Through these lamination rollers, media or a lamination sandwich of thermal print media and receiver stock can be fed. Having a high durometer of about 60-80 silicone material as the first deformable layer and the second deformable layer having a lower durometer of about 20-60 improves roller life greatly. The low durometer second layer allows for a larger nip while the high durometer first deformable layer increases the bond strength to the substantially solid layer and increasing the strength of the material at the area of highest stress.
The present invention relates to a drive roller assembly for conveying media, which is comprised of opposing lamination rollers. The lamination rollers of this assembly, which optionally can comprise a heater element, comprised of a substantially solid core, a first de-formable layer which surrounds the substantially solid core, a second de-formable layer which surrounds the first de-formable layer and forms an outer surface of one of the first and second opposing rollers or both.
The invention, and its objects and advantages, will become more apparent in the detailed description of the preferred embodiments presented below.